Its not a bad idea, as it has some smaller perks- running right on 14.7:1
gives less than ideal emissions and can be a bit sensitive to ping etc.
You can go quite rich before you significantly impact economy, even at
~12:1 it would be very difficult to measure a consistent drop in fuel economy
to any degree, and might even permit enough extra ignition advance or compression
on a given fuel octane. Exhaust valve temperatures vary almost perfectly
proportionate to mixture strengths. Volumetric efficiency is expressed
as a percentage, the theoretical amount of air that the engine should be
pumping at a given RPM divided by the actual amount of air that the
engine is pumping. Brent Covey

VOLUMETRIC EFFICIENCY ADDER TABLE ( $03C7 - $03D7)
The VE value used is the result of both tables summed.